Vacuum cleaners, such as upright vacuums, remove dirt from a carpet by creating a suction strong enough to draw the dirt particles from a section of the carpet up into the vacuum cleaner where the dirty air is passed through a vacuum bag in which the entrained dirt is captured. To increase the efficiency of this process, a base portion of the vacuum cleaner often has a roller brush for agitating dirt from the carpet as it is being vacuumed.
Inside the vacuum cleaner, a dirty air conduit transfers the dirty air from the base of the vacuum cleaner to the vacuum bag. The dirty air conduit runs up a handle assembly or, in cases where the dirty air conduit is rigid, the dirty air conduit can itself function as a portion of the handle. At the end of the dirty air conduit opposite the floor there is a dirty air outlet nozzle where the dirty air exits from the dirty air conduit. The vacuum bag is attached to the dirty air outlet nozzle.
The vacuum bag has a bag opening that fits closely over the dirty air outlet nozzle. The vacuum bag is otherwise a completely closed bag that is made from a porous material that allows air to flow through it, but which is too fine for most dirt particles to pass through. As dirty air passes through the vacuum bag, the air is forced through the porous material and the dirt is trapped in the bag. The bag thus collects the dirt from the dirty air and, more importantly, from the floor. Because the material of the vacuum bag is often fragile and can get very dusty, the vacuum bag is commonly held within a protective outer bag.
The outer bag is typically placed over the dirty air outlet nozzle first, with the dirty air outlet nozzle extending through a hole in the outer bag. A clip is then forced over the dirty air outlet nozzle between the outer bag and a protrusion on the outer surface of the dirty air outlet nozzle. The clip retains the outer bag in the proper position for use. Finally, the vacuum bag is placed over the remaining length of the dirty air outlet nozzle, and the outer bag closed.
To eliminate the need for emptying or cleaning the vacuum bag after it has collected dirt, vacuum bags have been modified over the years to be disposable. This allows the user to merely discard the dirty vacuum bag and replace it with a new, clean one. To adapt the vacuum bags for easy replacement, the bags have been designed so that the bag opening can be releasably engaged with the dirty air outlet nozzle.
One common vacuum bag design incorporates a reinforced area, known as a collar, surrounding the bag opening. The collar is usually a square or rectangular piece of thin cardboard. To install the vacuum bag, the user holds the collar by one or more edges, and forces the bag opening over the dirty air outlet nozzle. The collar can be designed with an elastic seal extending inward from the circumference of the bag opening to further seal the gap between the dirty air outlet nozzle and the bag opening.
Two primary problems exist with disposable vacuum bags. First, because the disposable vacuum bag is designed to be held within the outer bag, the dirty air outlet nozzle is often positioned deep within the outer bag and is hidden from sight. The user can initially look into the outer bag and see the dirty air outlet nozzle; however, when the vacuum bag is partially positioned for engagement with the dirty air outlet nozzle, the vacuum bag interferes with whatever unobscured view the user had of the dirty air outlet nozzle. As a result, the vacuum bag must be installed entirely be feel. Installing a vacuum bag by feel increases the possibility that the bag opening will not be properly aligned with the dirty air outlet nozzle when the installer pushes the collar onto the vacuum cleaner. If the collar is not aligned properly, forcing the collar onto the dirty air outlet nozzle can bend or break the collar. A vacuum bag with a bent or broken collar is more likely to leak or disengage during operation.
Another problem associated with disposable vacuum bags is that the vacuum bag is not held firmly to the dirty air outlet nozzle. The collar is often held onto the dirty air outlet nozzle by a small protrusion or a thin tab of cardboard. When the vacuum cleaner is turned on, the air rushing into the vacuum bag tends to urge the collar in a direction of disengagement from the dirty air outlet nozzle. As the vacuum bag fills, the pressure increases and, consequently, so does the force on the collar. If the collar is damaged during installation, or if the cardboard tab is not strong enough, the bag can disengage during operation, allowing dirty air to fill the outer bag. This results in the outer bag, which is not disposable, becoming soiled with dust and dirt.
Numerous different collar arrangements have been designed to retain the collar over the dirty air outlet nozzle. See, for example, U.S. Pat. No. 5,092,915 to Lackner; U.S. Pat. No. 5,064,455 to Lackner; U.S. Pat. No. 5,464,460 to Bosses; and U.S. Pat. No. 4,678,486 to Jacob et al. These designs generally incorporate protrusions on the dirty air outlet nozzle that engage with the collar. The interference between the protrusions and the collar retains the collar on the dirty air outlet nozzle. As with the traditional designs, if the collar is damaged, the vacuum bag can still leak or disengage from the dirty air outlet nozzle.
One invention, U.S. Pat. No. 5,688,298 to Bosses, attempts to solve the problem of aligning the vacuum bag with the dirty air outlet nozzle by adding an additional layer on the surface of the collar. The additional layer has a large, circular opening. The user can lightly press the face of the collar against the dirty air outlet nozzle and move the collar around until the dirty air outlet nozzle falls into the gap created by the additional layer. This lets the user know that the collar is in the proper position to be pressed against the dirty air outlet nozzle. This design does not incorporate any additional features to help retain the collar on the dirty air outlet nozzle.
One attempted solution to the problems of both alignment and retention is discussed in U.S. Pat. No. 5,089,038 to Kopko et al. This invention is designed for use with a vacuum cleaner having a rigid housing surrounding both the vacuum bag and the dirty air outlet nozzle. A hinge is integrally formed to the inside of the housing. A mounting plate holding the vacuum bag by its collar is attached to the hinge, and pivots to engage and disengage the vacuum bag from the dirty air outlet nozzle. The hinge is designed with positive stops to prevent the mounting plate from rotating too far. When the mounting plate is rotated to the point of engagement, the collar on the vacuum bag seals with the dirty air outlet nozzle. When the mounting plate is rotated to the point of disengagement, a user accessing the unit from the back of the housing may remove the vacuum bag from the mounting plate and replace it with a new one.
One problem associated with the Kopko et al. invention is that it is limited to use on vacuum cleaners having rigid housings. Without a rigid housing, the invention does not provide or suggest any place to attach the hinge. Another problem is that the hinge is designed with positive stops at the rotational limits. The mounting plate is thus only free to rotate over a limited angle. This limits the number of orientations in which the invention may be applied.
A need therefore exists for an improved bag docking assembly for aligning a vacuum bag with a dirty air outlet nozzle, and for retaining the vacuum bag in the position of engagement.